1. Field of the Invention
This invention relates to the sealing of valves or dampers, such as guillotine dampers, in which a closure member is completely removed from the fluid stream. In particular, the invention relates to sealing of such flow control devices utilizing pressurized gas, preferably air. The sealing air bleeds through seals which cooperate with the sealing member to ensure that the closure member effects a complete seal with respect to the fluid to be controlled, such as hot flue gases.
2. Description of the Prior Art
Guillotine dampers in which the closure member or damper blade is removed entirely from the flow path when the damper is opened and inserted into the flow path when the damper is closed are known in the art. It is also known to seal such dampers with the use of pressurized sealing gas, usually air.
In providing seals between a chamber of pressurized sealing and the main flow passageway through the damper, problems occur in the corners between seals. One such set of corners are the corners between the entry seal, through which the damper blade initially moves into the main flow passageway, and a set of lateral seals flanking the main flow passageway and into which the lateral edges of the damper blade extend when the damper blade is moved into the closed position. If corner gaps are formed under various bending conditions of the seals in various positions of the damper blade, the flow volume, power requirements and energy usage for providing the sealing air is greater than if the gaps can be avoided or minimized.